A survey of disease problems adversely affecting cultured shrimp at farms in Southern Taiwan was conducted in March of 1986. Farms selected for inclusion in the survey were experiencing a variety disease problems in their shrimp stocks, including mortality, poor growth, and reduced food conversion efficiency. Some apparently healthy cultured penaeid stocks were also sampled and examined for signs of subclinical disease. Most of the eight facilities surveyed cultured Penaeus monodon exclusively, although two also contained other species (P. penicillatus, P. vannamei, and P. semisulcatus). These were also sampled and examined. Important virus pathogens found during the survey included the P. monodon-type baculovirus (MBV) found in both P. monodon and P. semisulcatus, and infectious hypodermal and hematopoietic necrosis (IHHN) virus disease in P. vannamei. MBV was the most prevalent major pathogen encountered in the survey, and it was found in samples of P. monodon from seven of the eight locations surveyed and in the single sample of P. semisulcatus. These findings indicate that MBV is a common infectious agent in cultured stocks of these species in Taiwan. The disease hemocytic enteritis (HE) was also commonly observed in shrimp from five of the eight locations surveyed. This may indicate that the disease, which may be caused by an enteric toxin produced by certain types of blue-green algae, is an important disease of cultured shrimp in Taiwan. Also found in the study were two idiopathic syndromes which often, but not always, occurred together in the same shrimp. The first of these syndromes was a generalized diffuse inflammatory disease (II), which was found in several populations of P. monodon and in two stocks of P. penicillatus. The other idiopathic condition, often was observed in shrimp with II, was characterized by hypertrophy of Oka's lymphoid organ, and disassociation and metastasis of spherical clumps of cells derived from the hypertrophied organ. A number of apparently ubiquitous penaeid epicommensals were observed on the gills, appendages, and general body surface of many shrimp sampled in the survey, and some were associated with disease and mortality.
Fluctuation in the agglutinating antibody titer and changes in the properties of serum proteins have been investigated using gel filtration and electrophoresis during the course of the immune response of colored carp, Cyprinus carpio, against Aeromonas hydrophila. Fish were injected intraperitoneally with formalin killed A. hydrophila and reared at 21°C for five weeks. Agglutinating antibody titer rose one week after immunization and the highest titers ranging 1: 2, 048 to 8, 192 were observed four weeks after immunization. The serum of immunized carp was separated into four fractions by gel filtration with Sephadex G-200. Agglutinating activity was found only in the first fraction. Cellulose acetate membrane electrophoresis pattern did not show any difference in the protein composition between immunized and non-immunized fish sera. The agar gel immunoelectrophoresis pattern of the serum samples demonstrated that some proteins from the immunized fish shifted towards the anode in the area extending from the albumins to α-globulins. Polyacrylamide gel disc eletrophoresis showed an increase in concentration of proteins (Rm=0.10 to 0.15) which were eluted in the first fraction of gel filtration.
Plaque assays for salmonid virus, Oncorhynchus masou virus (OMV), were examined and compared with infectious haematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV), combining various fish cell-lines and three overlays. OMV produced the plaques only in chinook salmon embryo (CHSE-214) cells and rainbow trout gonad (RTG-2) cells, irrespective of overlays used, but plaque formation of IHNV and IPNV differed in different cell-lines according to the overlays used. The plaquing procedure using CHSE-214 cells gave a ten-fold higher number of plaques than RTG-2 cells. Among three overlays of methylcellulose, gum tragacanth, and agarose, methylcellulose overlay facilitated OMV plaque formation, and the plaques were most clearcut and easily enumerated. On the whole, the combination of methylcellulose overlay and CHSE-214 cell-line was the most suitable for plaque assay of OMV as well as IHNV and IPNV.
The role of protease in the pathogenicity of Vibrio anguillarum in experimental infections in Japanese eel (Anguilla japonica) and ayu (Plecoglossus altivelis), and its protective immunogenicity were investigated. It was confirmed antigenically that the pathogen produced the same protease in the experimentally infected fish as in vitro, though proteolytic activity was not detected. Pre-treatments with a sublethal dose of the protease by intramuscular injection in eels or by immersion in ayu enhanced the susceptibility of the fish to V. anguillarum. When an eel serum was treated in vitro with 10-50μg/ml of protease, the bactericidal activity of the serum was completely reduced. The protective immunogenicity of protease was demonstrated when the antigen was given to eels and ayu by injections. However, efficacy of the protease vaccine was overridden by its toxicity when ayu were vaccinated and challenged by immersion method.
Changes in myeloperoxidase(MPO)and glucosephosphate isomerase(GPI)activities in the neutrophil of the common carp, Cyprinus carpio, inflamed with turpentine were examined in this study. MPO activity continued to increase up to its maximum value(38.3±16.1×10-8) 12 h after the injection of turpentine at a dose of 1 ml/kg body weight, but soon reverted to the control level. On the other hand, GPI activity decreased 30 min after injection and the lowest activity(6.9±3.4×10-8) was observed after 1-3 h. The activity reverted to the control level after 24 h. These results, along with similar enzymatic studies on mammalian inflammation suggest that inflammation enhances the digestive ability of neutrophils in carp as well as in mammals.